In transport means, and in particular in aircraft, double-wall pipes are joined together to form pipelines for fuel systems. These pipes have an inner pipe and an outer pipe which surrounds the inner pipe while forming an intermediate space. The pipelines can then be used for example for supplying fuel to an additional turbine-driven auxiliary power unit in the rear of the aircraft or for connecting the trim tank, which is generally accommodated in the horizontal stabiliser, to the main tank of the aircraft.
The pipelines for aircraft should be designed with double walls in accordance with relevant safety and aviation regulations for the prevention of accidents.
Furthermore the use of the double-wall pipes for the purpose of heat transfer is possible. In this case a fluid flows through the inner pipe. Likewise a fluid flows through the space between the inner and the outer pipe, wherein a temperature difference exists between these two fluids. The flow direction is dependent upon the field of use and also the state of matter of the two fluids. The heat transfer is also influenced inter alia by the conductivity of the materials the two pipes. Possible fields of use are both in the construction of stationary and mobile equipment and in transport means.
Double-wall curved pipes have for example an outer pipe into which a hose is inserted coaxially. The distance between the hose and the outer pipe is ensured by spacers which support the hose coaxially with respect to the outer pipe. For geometric reasons, however, it may be that a rigid bent inner pipe cannot be integrated (or inserted) into a similarly shaped outer pipe, as is the case in particular with substantial or multiple curvatures.
DE 10 2005 028 766 B4 and US 2009/0025815 A1 describe curved pipelines with a metal inner pipe. During production a support core made from polystyrene is laid around the inner pipe and is then wrapped around with fibre-reinforced epoxy resin material. After the curing of the outer pipe produced in this way from fibre-reinforced epoxy resin material the support core of polystyrene is removed by washing out with a solvent.
Other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.